Garments designed for the outerwear market can be divided into several main categories including hard shell and soft shell garments respectively. In general, hard shell garments may be distinguished by the inclusion of a waterproofing barrier such as an applied coat of urethane. While soft shell garments can include tightly woven fabrics giving the garment a measure of water repellency, they are generally not completely waterproof. Fleeces having soft fabric which is generally of a knit construction are also used in the outerwear market, and these too are normally not waterproof to the degree that hard shell garments are.
Because hard shell garments are used during athletic and outdoor activities, it is desirable that they be light, rugged, have good waterproof characteristics and feature a moisture transfer membrane or the like for moisture management. In addition, from the manufacturer's point of view it is desirable that these garments be relatively simple to manufacture.
The method of joining panels of fabric to assemble a complete garment can be just as important to that garment's overall characteristics as the type of fabric used in that garment. While several prior art methods exist for forming seams in hard shell garments, each has its drawbacks. Simple threaded stitching, while commonly used in the garment industry, is problematic in hard shell garments because a completed stitch leaves a bulky seam in the otherwise lightweight fabric of a hard shell garment. Furthermore, the passage of the needle through the fabric of the garment compromises the waterproof nature of the fabric, necessitating the application of a seam tape secured with an adhesive over the stitched seam to ensure a waterproof seal.
However, gluing a length of seam tape over the stitched seam creates a new problem. Namely, a sewn and taped seam tends to be rather stiff. The differential in stiffness between the taped seam formed by this process and the lightweight fabric joined by the sewn and taped seam leads to a phenomenon known as edge abrasion.
Because the region of the seam is much bulkier than the fabric panel which it joins, it causes a region of wear to build up just at the point where the fabric panel meets the taped seam. The continual flexing of the loose fabric against the stiff edge of the taped seam and any external abrasion causes the fabric to wear through at that point, reducing the life of an otherwise serviceable garment.
Alternatively, manufacturers have employed adhesives to join panels of fabric in a “stitchless” garment. Typically, what is known as a lap seam is made when two pieces of fabric are precut and overlapped. The pieces are secured with an adhesive applied in the area of overlap, which in some instances may require heating to fully interlock with the fibers of the fabric pieces.
However, the fabrics used in hard shell garments are usually either very tightly woven and/or have a durable water repellent (“DWR”) finish applied to the fabric surface to provide waterproofing for the fabric. A fair amount of adhesive must be applied to find purchase and make a bond of sufficient strength with a fabric having such a weave or finish, making the overall seam that much stiffer once the adhesive has solidified. As such, this method of stitchless garment construction can create an even stiffer seam than that of the sewn and taped seam described above, and so garments constructed with this process can suffer from the problem of edge abrasion to an even greater degree. Also, some fabrics cannot be reliably bonded in this manner and can fail in use.